Python function call handler
A call handler is a method used to process each Python function call. When creating a function version, you should specify an entry point that consists of a file name and a call handler name (such as, main.handler
).
Note
At any given time, a single function instance processes only one request. This allows you to use global variables without having to provide data integrity control.
When invoking the handler, the runtime provides the following arguments:
-
Request body (
event
parameter):- If the request body is a JSON document, it will be converted to
dict
using thejson.loads
method. - If a function was invoked with the
?integration=raw
request string parameter, the HTTP request body is provided to the function as is (unprocessed).
- If the request body is a JSON document, it will be converted to
-
Invocation context (
context
parameter).The context contains the necessary information about the function version. The structure of this object is described in Python function invocation context.
Handler types
A function can use both synchronous and asynchronous request handlers.
Synchronous handler
To have the output returned, use the return
statement or raise an exception using the raise
statement. A synchronous function must return a result or throw an exception.
Asynchronous handler
A handler can be an async def
asynchronous function. In this case you can use the following statements:
return
: Returns the function response.raise
: Reports an error to the runtime environment.await
: Tracks the execution of asynchronous function invocations.
Note
The service only supports the asyncio
library as a runtime environment for asynchronous functions.
For more information about development using async/await
, see the relevant documentation section
Examples
HTTP request structure output
The following function outputs the request structure and invocation context to both the execution log and function response:
import json
def handler(event, context):
return {
'statusCode': 200,
'body': json.dumps(
{
'event': event,
'context': context,
},
default=vars,
),
}
Function invocation example:
curl --data '{"hello": "world"}' -H 'Content-Type: application/json' https://functions.yandexcloud.net/d4eo2faf62**********?param=one
Result:
{
"context": {
"aws_request_id": "6e8356f9-489b-4c7b-8ba6-c8cd74f25455",
"deadline_ms": 1657713543198,
"function_name": "d4eo2faf62**********",
"function_version": "d4e3vrugh3**********",
"invoked_function_arn": "d4eo2faf62**********",
"log_group_name": "ckgjmanjlh**********",
"log_stream_name": "d4e3vrugh3**********",
"memory_limit_in_mb": 128,
"request_id": "6e8356f9-489b-4c7b-8ba6-c8cd74f25455",
"token": {
"access_token": "<IAM token>",
"expires_in": 42299,
"token_type": "Bearer"
}
},
"event": {
"body": "{\"hello\": \"world\"}",
"headers": {
"Accept": "*/*",
"Content-Length": "18",
"Content-Type": "application/json",
"Host": "functions.yandexcloud.net",
"User-Agent": "curl/7.64.1",
"X-Forwarded-For": "109.252.148.209",
"X-Real-Remote-Address": "[109.252.148.209]:2816",
"X-Request-Id": "6e8356f9-489b-4c7b-8ba6-c8cd74f25455",
"X-Trace-Id": "e9fe9b05-c1aa-4fb8-94d8-a514fd6f3ff7"
},
"httpMethod": "POST",
"isBase64Encoded": false,
"multiValueHeaders": {
"Accept": [
"*/*"
],
"Content-Length": [
"18"
],
"Content-Type": [
"application/json"
],
"Host": [
"functions.yandexcloud.net"
],
"User-Agent": [
"curl/7.64.1"
],
"X-Forwarded-For": [
"109.252.148.209"
],
"X-Real-Remote-Address": [
"[109.252.148.209]:2816"
],
"X-Request-Id": [
"6e8356f9-489b-4c7b-8ba6-c8cd74f25455"
],
"X-Trace-Id": [
"e9fe9b05-c1aa-4fb8-94d8-a514fd6f3ff7"
]
},
"multiValueParams": {},
"multiValueQueryStringParameters": {
"param": [
"one"
]
},
"params": {},
"pathParams": {},
"queryStringParameters": {
"param": "one"
},
"requestContext": {
"httpMethod": "POST",
"identity": {
"sourceIp": "109.252.148.209",
"userAgent": "curl/7.64.1"
},
"requestId": "6e8356f9-489b-4c7b-8ba6-c8cd74f25455",
"requestTime": "13/Jul/2022:11:58:59 +0000",
"requestTimeEpoch": 1657713539
},
"url": ""
}
}